#### § 218.234 Mitigation.

When conducting activities identified in § 218.230, the mitigation measures described in this section and in any LOA issued under §§ 216.106 of this chapter and 218.237 must be implemented.

(a) *Personnel training—lookouts.* The Navy will utilize one or more trained marine biologists qualified in conducting at-sea marine mammal visual monitoring to conduct at-sea marine mammal visual monitoring training and qualify designated ship personnel to conduct at-sea visual monitoring. Training will ensure quick and effective communication within the command structure in order to facilitate implementation of protective measures if they detect marine mammals and may be accomplished either in-person, or via video training.

(b) *General operating procedures.*

(1) Prior to SURTASS LFA sonar activities, the Navy will promulgate executive guidance for the administration, execution, and compliance with the environmental regulations under these regulations and LOA.

(2) The Navy must not transmit the SURTASS LFA sonar signal at a frequency greater than 500 Hz.

(c) *2,000-yard LFA sonar mitigation zone; suspension and delay.* If a marine mammal is detected, through monitoring required under § 218.235, within or about to enter within 2,000 yards of the SURTASS LFA source (*i.e.,* the LFA mitigation zone), the Navy must immediately delay or suspend SURTASS LFA sonar transmissions.

(d) *Resumption of SURTASS LFA sonar transmissions.*

(1) The Holder of a LOA may not resume SURTASS LFA sonar transmissions earlier than 15 minutes after:

(i) All marine mammals have left the area of the 2,000-yard LFA sonar mitigation zone; and

(ii) There is no further detection of any marine mammal within the 2,000-yard LFA sonar mitigation zone as determined by the visual, passive acoustic, and active acoustic high frequency monitoring described in § 218.235.

(2) [Reserved]

(e) *Ramp-up procedures for the high-frequency marine mammal monitoring (HF/M3) sonar required under § 218.235.*

(1) The Navy must ramp up the HF/M3 sonar power level beginning at a maximum source sound pressure level of 180 dB: re 1 μPa at 1 meter in 10-dB increments to operating levels over a period of no less than five minutes:

(i) At least 30 minutes prior to any SURTASS LFA sonar transmissions; and

(ii) Anytime after the HF/M3 source has been powered down for more than two minutes.

(2) The Navy must not increase the HF/M3 sound pressure level once a marine mammal is detected; ramp-up may resume once marine mammals are no longer detected.

(f) *Geographic restrictions on the SURTASS LFA sonar sound field.*

(1) LFA sonar training and testing activities must be conducted such that:

(i) The received level of SURTASS LFA sonar transmissions will not exceed 180 dB re: 1 μPa rms within 22 km (12 nmi) from any emergent land, including offshore islands;

(ii) The received level of SURTASS LFA sonar transmissions will not exceed 180 dB re: 1 μPa rms at a distance of 1 km (0.5 nmi) seaward of the outer perimeter of any Offshore Biologically Important Area (OBIA) designated in the Study Area for SURTASS LFA sonar in paragraph (f)(2) of this section, or subsequently identified through the Adaptive Management process specified in § 218.241, during the period specified. The boundaries and periods of such OBIAs will be kept on file in NMFS' Office of Protected Resources and on its website at *https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.*

(iii) No more than 25 percent of the authorized amount (transmission hours) of SURTASS LFA sonar for training and testing will be conducted within 10 nmi (18.5 km) of any single OBIA during any year (no more than 124 hours in years 1-4 and 148 hours in years 5-7) unless the following conditions are met: Should national security present a requirement to conduct more than 25 percent of authorized hours of SURTASS LFA sonar within 10 nmi (18.5 km) of any single OBIA during any year, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with notification as soon as is practicable and include the information (*e.g.,* sonar hours) in its annual activity reports submitted to NMFS.

(iv) No activities with the SURTASS LFA system will occur within territorial seas of foreign nations, which are areas from 0 up to 12 nmi from shore, depending on the distance that individual nations claim; and

(v) No activities with the SURTASS LFA sonar system will occur in the waters of Penguin Bank, Hawaii (defined as water depth of 600 ft (183 m)), and ensonification of Hawaii state waters (out to 3 nmi) will not exceed 145 dB re: 1 μPa rms.

(2) Offshore Biologically Important Areas (OBIAs) for marine mammals (with specified periods) for SURTASS LFA sonar training and testing activities include the following (Table 1 to paragraph (f)(2)):

| OBIA name | Ocean area | Effective seasonal period |
| --- | --- | --- |
| Main Hawaiian Islands | Central North Pacific | November to April. |
| Northwestern Hawaiian Islands | Central North Pacific | December to April. |
| Mariana Islands | Western North Pacific | February to April. |
| Ryukyu-Philippines | Western North Pacific | January to April. |
| Ogasawara Islands (Sperm Whale) | Western North Pacific | June to September. |
| Ogasawara-Kazin Islands (Humpback Whale) | Western North Pacific | December to May. |
| Honshu | Western North Pacific | January to May. |
| Southeast Kamchatka | Western North Pacific | June to September. |
| Gulf of Thailand | Eastern Indian Ocean | April to November. |
| Western Australia (Blue Whale) | Eastern Indian Ocean | May to November. |
| Western Australia (Humpback Whale) | Eastern Indian Ocean | May to December. |
| Southern Bali | Eastern Indian Ocean | October to November. |
| Swatch-of-No-Ground (SoNG) | Northern Bay of Bengal | Year-round. |
| Sri Lanka | Eastern Indian Ocean | October to April. |

Table 1 to Paragraph (f)(2)—Offshore Biologically Important Areas (OBIAs)

(g) *Minimization of additional harm to live-stranded (or milling) mammals.* The Navy must consult the Notification and Reporting Plan, which sets out the requirements for when live stranded marine mammals are reported in the Study Area. The Stranding and Notification Plan is available at: *https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-navy-operations-surveillance-towed-array-sensor-system-0.*